1

EQ573 Equaliser / EQ573II - Lowband 70Hz - faint-to-no audio when selected

« on: August 29, 2022, 07:13:21 AM »

Hi JP,

So I finished building my 2nd EQ573II now that I got the replacement rotary knobs (thanks for the quick shipment!). 

All seems to work fine EQ-wise (haven't fully tested with preamp just yet), but I am having an annoying issue with lowband knob - when selecting thge 70 Hz filter specifically, it quiets down to extremely low-volume to no audio at all when source is not very loud. 
All other bands/off seem to work fine. 
Same for other knobs/selectors.

I doublechecked all solder joints, in looking at the schematic I was trying to figure out the signal flow when 70Hz is selected but I got a bit lost.

What would cause this? Which component(s) and traces that specifically are related to 70Hz selection, should I check?

Thank you.

Tal

2

EQ573 Equaliser / 3 pin connector cable!!

« on: June 29, 2022, 09:38:24 PM »

Hi,

I've had a heck of a time trying to put together this cable, as embarrassing as that sounds. 
I've put together 10+ DIY units but stripping & terminating cables properly isn't my forte I guess.
And now I've damaged the crimps and shortened the cable a lot trying to cut-redo-cut-redo-cut-redo and it's still not even and the balancing wire always ends up too short or long.

Would any 3-pin female-to-female connector work if I went and bought one on Amazon or elsewhere? Or does it have to be shielded/balanced? 

Would something like this (little longer though) work? 

https://www.amazon.com/dp/B00O9Y8HYO?psc=1&ref=ppx_yo2ov_dt_b_product_details

3

TS500 Tape Simulator / Unit gain & calibration issues

« on: June 16, 2022, 11:09:28 PM »

(Copy/paste from email sent to JP for help and hoping to get response via here)

Hi JP,
 
I have the 2 of the TS500’s bought ~1.5 months apart.
 
I have not been able to get them both to behave the same in terms of output and VAC/db measures even with continuous recalibrations of both.
 
In short and before I dive into all the results and steps – the first question I need help answered is on the following test condition I did:
 

Conditions	Switch position		Output voltage (VAC)	Output voltage (VAC)
input signal = sine 1kHz, 1VAC	Units out of 500 Lunchbox		1.001	1.003
input signal = sine 1kHz, 1 VAC	Units installed in 500. TS500 is OFF	* Levels are ~-1.0db differenece without units being switched to ON	0.861	0.959

 
 
As you see, without any unit being installed in my 500 Rack (Cranborne 500ADAT slots 13 & 14 in this case), for the same Sine wave I get nearly identical output VAC and db in my DAW with a negligible difference on the right side.
However, where I am stomped is – even when the units are in OFF position, with DRIVE on 0 just in case (I know it’s not supposed to affect when in OFF), and OUTPUT on 10 – I am getting a large difference out of the box already between L & R units.
 
Need some guidance as to what would cause this as I thought these are “true bypass” and yet I am getting this difference. 
 
Thank you in advance.